Experimentally induced spinal nociceptive sensitization increases with migraine frequency: a single-blind controlled study

Spinal hyperexcitability in patients with chronic musculoskeletal pain or headache as evidenced by alterations in the nociceptive withdrawal reflex: a systematic review and meta-analysis

ABSTRACT

The nociceptive withdrawal reflex (NWR) is a spinal withdrawal reflex induced by painful stimulation. It is a measure of spinal hyperexcitability, which is believed to contribute to chronic musculoskeletal pain (MSKP) and headache. Previous syntheses of the evidence for alterations in the NWR in patients with chronic MSKP and headache needed a comprehensive update. This systematic review and meta-analysis was performed after the Preferred Items for Systematic reviews and Meta-Analyses guidelines. Studies examining NWR-related outcome measures in patients with chronic MSKP and headache compared to pain-free controls were identified through electronic database searches and included after screening against predefined eligibility criteria. Standardized mean differences or mean differences and 95% confidence intervals (CI) were calculated. Thirty-one studies were included in the systematic review and 25 in the meta-analysis. Moderate-quality evidence was found indicating lower NWR threshold (-3.68; 95% CI, -4.56 to -2.80; P < 0.001), larger NWR area (standardized mean difference = 0.69; 95% CI, 0.37-1.01; P < 0.001), and shorter NWR latency (mean difference = -13.68; 95% CI, -22.69, -4.67; P = 0.003) in patients compared to controls. These findings remained robust when performing meta-regressions based on subgroups (ie, headache, fibromyalgia, whiplash-associated disorder, and osteoarthritis). Low-quality evidence demonstrated facilitated temporal summation of NWR threshold (-2.48; 95% CI, -3.13 to -1.83; P < 0.001) in patients compared to controls. Spinal hyperexcitability as evidenced by lowered NWR threshold values and temporal summation of the NWR is present in patients with chronic MSKP and headache. No evidence was found for alterations in NWR duration and NWR magnitude. Future research is needed to address the gap in research on NWR-related outcome measures other than NWR threshold.

General physical impairments in migraine patients beyond cervical function

Previous research has focused on the possibility of cervical dysfunction in migraine patients, similar to what is observed in patients with tension-type headaches. However, there is no evidence concerning the physical function of other body regions, even though lower levels of physical activity have been reported among migraine patients. The aim of this study was to compare cervical and extra-cervical range of motion, muscular strength, and endurance, as well as overall levels of physical activity, between patients with chronic migraine (CM) and asymptomatic participants. The secondary objective included the analysis of associations between CM-related disability and various physical and psychological variables. A total of 90 participants were included in this cross-sectional study: 30 asymptomatic participants (AG) and 60 patients with CM. Cervical and lumbar range of motion, strength and endurance, as well as handgrip strength were measured. Headache-related disability, kinesiophobia, pain behaviors, physical activity level and headache frequency were assessed through a self-report. Lower values were found in CM vs AG for cervical and lumbar ranges of motion (p < 0.05; effect sizes ranging from 0.57 to 1.44). Also, for neck extension strength (p = 0.013; d = - 0.66), lumbar strength (p < 0.001; d = - 1.91) and handgrip strength (p < 0.001; d = - 0.98), neck endurance (p < 0.001; d = - 1.81) and lumbar endurance (p < 0.001; d = - 2.11). Significant differences were found for physical activity levels (p = 0.01; d = - 0.85) and kinesiophobia (p < 0.001; d = - 0.93) between CM and AG. Headache-related disability was strongly associated with headache frequency, activity avoidance, and rest, which together explained 41% of the variance. The main findings of this study suggest that patients with CM have a generalized fitness deficit and not specifically cervical dysfunction. These findings support the hypothesis that migraine patients have not only neck-related issues but also general body conditions.

Pain profiling in migraine: a systematic review of Quantitative Sensory Testing (QST), Conditioned Pain Modulation (CPM), and Corneal Confocal Microscopy (CCM)

OBJECTIVE

The aim of this systematic review is to identify pain profiling parameters that are reliably different between patients with migraine and healthy controls, using Quantitative Sensory Testing (QST) including Temporal Summation (TS), Conditioned Pain Modulation (CPM), and Corneal Confocal Microscopy (CCM).

METHODS

A comprehensive literature search was conducted (up to 23 May 2024). The quality of the research was assessed using the Newcastle-Ottawa Scale (NOS) for non-randomized studies.

RESULTS

Twenty-eight studies were included after screening. The QST studies indicate that migraine patients exhibit lower pressure pain thresholds (PPT), particularly in the trigeminal region. A previous meta-analysis reported lower heat pain thresholds (HPT). CPM studies suggest a (mild) inhibitory or absent response in migraine patients, not different from controls. High-frequency and chronic migraine patients may exhibit a facilitatory CPM response. With repeated executions of CPM, migraine patients display a diminishing CPM response, a phenomenon not observed in control subjects. CCM investigations in migraine patients revealed conflicting outcomes, likely as a result of small sample sizes and limited characterization of migraine features.

CONCLUSION

Pain profiling migraine patients varies due to sensory modality, applied methods, anatomical sites, and migraine features. Understanding pain profiling offers insights into migraine pathophysiology, requiring careful selection of parameters and differentiation among migraine subtypes.

High-frequency episodic migraine: Time for its recognition as a migraine subtype?

BACKGROUND

High-frequency episodic migraine (HFEM) has gained attention in the field of headache research and clinical practice. In this narrative review, we analyzed the available literature to assess the evidence that could help decide whether HFEM may represent a distinct clinical and/or biological entity within the migraine spectrum.

METHODS

The output of the literature search included 61 papers that were allocated to one of the following topics: (i) socio-demographic features and burden; (ii) clinical and therapeutic aspects; (iii) pathophysiology; and (iv) classification.

RESULTS

Multiple features differentiate subjects with HFEM from low-frequency episodic migraine and from chronic migraine: education, employment rates, quality of life, disability and psychiatric comorbidities load. Some evidence also suggests that HFEM bears a specific profile of activation of cortical and spinal pain-related pathways, possibly related to maladaptive plasticity.

CONCLUSIONS

Subjects with HFEM bear a distinctive clinical and socio-demographic profile within the episodic migraine group, with a higher disease burden and an increased risk of transitioning to chronic migraine. Recognizing HFEM as a distinct entity is an opportunity for the better understanding of migraine and the spectrum of frequency with which it can manifest, as well as for stimulating further research and more adequate public health approaches.

Expression of miR-155 in monocytes of people with migraine: association with phenotype, disease severity and inflammatory profile

BACKGROUND

miR-155 is involved in the generation and maintenance of inflammation and pain, endothelial function and immune system homeostasis, all functions that are relevant for migraine. The present study aims to assess the levels of miR-155 in migraine subtypes (episodic and chronic) in comparison to age- and sex-matched healthy controls.

METHODS

This is a cross-sectional, controlled, study involving three study groups: I) episodic migraine (n = 52, EM), II) chronic migraine with medication overuse (n = 44, CM-MO), and III) healthy controls (n = 32, HCs). We assessed the interictal gene expression levels of miR-155, IL-1β, TNF-α, and IL-10 in peripheral blood monocytes using rtPCR. The monocytic differentiation toward the M1 (pro-inflammatory) or M2 (anti-inflammatory) phenotypes was assessed in circulating monocytes with flow cytometry analysis and cell sorting.

RESULTS

miR-155 gene expression was higher in CM-MO group (2.68 ± 2.47 Relative Quantification - RQ) when compared to EM group (1.46 ± 0.85 RQ, p = 0.006) and HCs (0.44 ± 0.18 RQ, p = 0.001). In addition, miR-155 gene expression was higher in EM group when compared to HCs (p = 0.001). A multivariate analysis confirmed the difference between EM and CM-MO groups after correction for age, sex, smoking habit, preventive treatment, aura, presence of psychiatric or other pain conditions. We found higher gene expression of IL-1β, TNF-α, and lower gene expression of IL-10 in migraine participants when compared to HCs (p = 0.001 for all comparisons). TNF-α and IL-10 genes alterations were more prominent in CM-MO when compared to EM participants (p = 0.001). miR-155 positively correlated with IL-1β (p = 0.001) and TNF-α (p = 0.001) expression levels. Finally, in people with CM-MO, we described an up-regulated percentage of events in both M1 and M2 monocytic profiles.

CONCLUSIONS

Our study shows for the first time a specific profile of activation of miR-155 gene expression levels in monocytes of selected migraine subpopulations, more pronounced in subjects with CM-MO. Interestingly, mir-155 expression correlated with markers of activation of the inflammatory and immune systems. The CM-MO subpopulation showed a peculiar increase of both pro-inflammatory and anti-inflammatory monocytes which worths further investigation.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov . (NCT05891808).

sEMG Biofeedback for Episodic Migraines: A Pilot Randomized Clinical Trial

The aim of this study was to assess the feasibility and potential effectiveness of a 6-week virtual sEMG biofeedback intervention for patients with episodic migraines. Patients with episodic migraines were randomized to treatment with a novel surface EMG (sEMG) at-home biofeedback device or a treatment as usual control group; they completed validated baseline and post-intervention assessments of migraine related disability (migraine-specific quality of life, anxiety and depression). Participants also underwent a series of Quantitative Sensory Testing (QST) procedures referring to several different tests that quantitatively assess responses to mechanical stimuli during two separate visits (baseline and post intervention). No adverse events were reported during the study. Compared to the treatment as usual comparison group, patients in the sEMG biofeedback group reported lower migraine disability (p < 0.05). Compared to baseline, participants in the sEMG biofeedback group demonstrated statistically significant reductions in anxiety (p < 0.01), and significant increases in quality of life (p < 0.001), and significant decreases in temporal summation (p < 0.05) assessed by QST. No significant changes were observed in any of the outcomes in the control comparison group (p > 0.05). No significant changes were observed in migraine frequency in either of the two groups (p > 0.05). In addition, mediation analyses revealed that changes in migraine related quality of life mediated group effects on changes in migraine disability. Virtual sEMG biofeedback shows promise as a potential therapy for reducing disability, anxiety and depression and improving quality of life in individuals with episodic migraines. These results demonstrate the feasibility of a digital intervention for migraines and set the basis for conducting a future, larger scale randomized controlled trial to confirm these preliminary findings.

Trigeminocervical pain sensitivity during the migraine cycle depends on headache frequency

OBJECTIVE

This experimental study aimed to assess pain sensitivity in low-frequency episodic migraine (LFEM), high-frequency episodic migraine (HFEM), and chronic migraine (CM) patients across the different phases of the migraine cycle.

METHOD

In this observational, experimental study, clinical characteristics (diary and time from the last/next headache attack), and quantitative sensory testing (QST) (wind-up pain ratio (WUR) and pressure pain threshold (PPT) from the trigeminal area and PPT from the cervical spine) was performed. LFEM, HFEM, and CM were assessed in each of the 4 migraine phases (HFEM and LFEM: interictal, preictal, ictal, and postictal; CM: interictal and ictal) and compared vs. each other's (matched for the phase) and controls.

RESULTS

A total of 56 controls, 105 LFEM, 74 HFEM, and 32 CM were included. No differences in QST parameters were observed between LFEM, HFEM, and CM in any of the phases. During the interictal phase and when comparing with controls the following were found: 1) LFEM had lower trigeminal PPT (p = 0.001) and 2) lower cervical PPT (p = 0.001). No differences were observed between HFEM or CM and healthy controls. During the ictal phase and when comparing with controls the following were found: HFEM and CM had 1) lower trigeminal PPTs (HFEM p = 0.001; CM = p < 0.001), 2) lower cervical PPT s (HFEM p = 0.007; CM p < 0.001), and 3) higher trigeminal WUR (HFEM p = 0.001, CM p = 0.006). No differences were observed between LFEM and healthy controls. During the preictal phase and when comparing with controls the following were found: 1) LFEM had lower cervical PPT (p = 0.007), 2) HFEM had lower trigeminal (p = 0.013) and 3) HFEM had lower cervical (p = .006) PPTs. During the postictal phase and when comparing with controls the following were found: 1) LFEM had lower cervical PPT (p = 0.003), 2) HFEM had lower trigeminal PPT (p = 0.005), and 3) and HFEM had lower cervical (p = 0.007) PPTs.

CONCLUSION

This study suggested that HFEM patients have a sensory profile matching CM better than LFEM. When assessing pain sensitivity in migraine populations, the phase with respects to headache attacks is of utmost importance and can explain the inconsistency in pain sensitivity data reported in the literature.

Profiling migraine patients according to clinical and psychophysical characteristics: a cluster analysis approach

AIM

This study aims to profile migraine patients according clinical and psychophysical characteristics.

METHOD

In this observational study, two cohorts of migraine patients(episodic/chronic) were included. Cohort-1: ictal/perictal phase; Cohort-2: interictal phase.The following variables were assessed: headache frequency; disability; cervical active range of motion(AROM) in flexion, extension, right/left lateral flexion, right/left rotation; pressure-pain threshold(PPT) over: temporalis, two cervical areas(C1/C4 vertebral segments), and two distal pain-free areas(hand/leg). Cluster analysis was performed using the K-means algorithm. Differences across clusters were investigated.

RESULTS

Cohort-1: 100 patients were included, and two clusters were identified. Cluster-1.1 (19%), Cluster-1.2 (81%). Cluster 1.1 had a higher percentage of men (P = .037) and higher disability (P = .003) compared to Clusters 1.2. Cluster 1.2 had reduced AROM in flexion, extension, and left/right lateral flexion (P < .037), and lower PPT value in all areas (P < .001) compared to Cluster 1.1. Cohort-2: 98 patients were included and three clusters were identified. Cluster-2.1(18%), Cluster-2.2(45%), and Cluster-2.3(37%). Cluster-2.1 had a higher percentage of men compared to clusters-2.2 and 2.3 (P = .009). Cluster-2.3 had higher headache frequency, and disability compared to Cluster-2.2 (P < .006), and higher disability compared to Cluster-2.1 (P = .010). Cluster-2.3 had reduced AROM in all directions compared to Clusters-2.1 and 2.2 (P < .029). Clusters-2.2 and 2.3 have lower PPT values in all areas compared to Cluster-1.1 (P < .001).

CONCLUSION

In the Ictal/perictal phase, two clusters were identified according to clinical and psychophysical characteristics, with one group showing no psychophysical impairment and one with increased pain-sensitivity and cervical musculoskeletal-dysfunctions.In the interictal phase, three clusters could be identified, with one group showing no psychophysical impairment, one increased pain-sensitivity, and one increased pain sensitivity and cervical musculoskeletal-dysfunctions.

Smooth muscle ATP-sensitive potassium channels mediate migraine-relevant hypersensitivity in mouse models

BACKGROUND

Opening of KATP channels by systemic levcromakalim treatment triggers attacks in migraine patients and hypersensitivity to von Frey stimulation in a mouse model. Blocking of these channels is effective in several preclinical migraine models. It is unknown in what tissue and cell type KATP-induced migraine attacks are initiated and which KATP channel subtype is targeted.

METHODS

In mouse models, we administered levcromakalim intracerebroventricularly, intraperitoneally and intraplantarily and compared the nociceptive responses by von Frey and hotplate tests. Mice with a conditional loss-of-function mutation in the smooth muscle KATP channel subunit Kir6.1 were given levcromakalim and GTN and examined with von Frey filaments. Arteries were tested for their ability to dilate ex vivo. mRNA expression, western blotting and immunohistochemical stainings were made to identify relevant target tissue for migraine induced by KATP channel opening.

RESULTS

Systemic administration of levcromakalim induced hypersensitivity but central and local administration provided antinociception respectively no effect. The Kir6.1 smooth muscle knockout mouse was protected from both GTN and levcromakalim induced hypersensitivity, and their arteries had impaired dilatory response to the latter. mRNA and protein expression studies showed that trigeminal ganglia did not have significant KATP channel expression of any subtype, whereas brain arteries and dura mater primarily expressed the Kir6.1 + SUR2B subtype.

CONCLUSION

Hypersensitivity provoked by GTN and levcromakalim in mice is dependent on functional smooth muscle KATP channels of extracerebral origin. These results suggest a vascular contribution to hypersensitivity induced by migraine triggers.

Expression of Selected microRNAs in Migraine: A New Class of Possible Biomarkers of Disease?

Preliminary but convergent findings suggest a role for microRNAs (miRNAs) in the generation and maintenance of chronic pain and migraine. Initial observations showed that serum levels of miR-382-5p and miR-34a-5p expression were increased in serum during the migraine attack, with miR-382-5p increasing in the interictal phase as well. By contrast, miR-30a-5p levels were lower in migraine patients compared to healthy controls. Of note, antimigraine treatments proved to be capable of influencing the expression of these miRNAs. Altogether, these observations suggest that miRNAs may represent migraine biomarkers, but several points are yet to be elucidated. A major concern is that these miRNAs are altered in a broad spectrum of painful and non-painful conditions, and thus it is not possible to consider them as truly “migraine-specific” biomarkers. We feel that these miRNAs may represent useful tools to uncover and define different phenotypes across the migraine spectrum with different treatment susceptibilities and clinical features, although further studies are needed to confirm our hypothesis. In this narrative review we provide an update and a critical analysis of available data on miRNAs and migraines in order to propose possible interpretations. Our main objective is to stimulate research in an area that holds promise when it comes to providing reliable biomarkers for theoretical and practical scientific advances.

Spinal nociceptive sensitization and plasma palmitoylethanolamide levels during experimentally induced migraine attacks

ABSTRACT

Migraine pathophysiology has been suggested to include dysregulation of the endocannabinoid system (ES). We simultaneously evaluated plasma anandamide (AEA) and palmitoylethanolamide (PEA) levels and spinal sensitization in a validated human model of migraine based on systemic nitroglycerin (NTG) administration. Twenty-four subjects with episodic migraine (MIG) and 19 healthy controls (HC) underwent blood sampling and investigation of nociceptive withdrawal reflex thresholds (RTh: single-stimulus threshold; TST: temporal summation threshold) before and 30 (T30), 60 (T60), and 120 (T120) minutes after sublingual NTG administration (0.9 mg). At baseline, the MIG and HC groups were comparable for plasma AEA (P = 0.822) and PEA (P = 0.182) levels, and for RTh (P = 0.142) and TST values (P = 0.150). Anandamide levels increased after NTG administration (P = 0.022) in both groups, without differences between them (P = 0.779). By contrast, after NTG administration, PEA levels increased in the MIG group at T120 (P = 0.004), while remaining stable in the HC group. Nitroglycerin administration induced central sensitization in the MIG group, which was recorded as reductions in RTh (P = 0.046) at T30 and T120, and in TST (P = 0.001) at all time points. In the HC group, we observed increases in RTh (P = 0.001) and TST (P = 0.008), which suggest the occurrence of habituation. We found no significant correlations between the ES and neurophysiological parameters. Our findings suggest a role for PEA in the ictal phase of episodic migraine. The ES does not seem to be directly involved in the modulation of NTG-induced central sensitization, which suggests that the observed PEA increase and spinal sensitization are parallel, probably unrelated, phenomena.

CGRP-dependent signalling pathways involved in mouse models of GTN- cilostazol- and levcromakalim-induced migraine

BACKGROUND

Knowledge of exact signalling events during migraine attacks is lacking. Various substances are known to trigger migraine attacks in patients and calcitonin gene-related peptide antagonising drugs are effective against migraine pain. Here, we investigated the signalling pathways involved in three different mouse models of provoked migraine and relate them to calcitonin gene-related peptide and other migraine-relevant targets.

METHODS

In vivo mouse models of glyceryl trinitrate-, cilostazol- and levcromakalim-induced migraine were applied utilising tactile sensitivity to von Frey filaments as measuring readout. Signalling pathways involved in the three models were dissected by use of specific knockout mice and chemical inhibitors. In vivo results were supported by ex vivo wire myograph experiments measuring arterial dilatory responses and ex vivo calcitonin gene-related peptide release from trigeminal ganglion and trigeminal nucleus caudalis from mice.

RESULTS

Glyceryl trinitrate-induced hypersensitivity was dependent on both prostaglandins and transient receptor potential cation channel, subfamily A, member 1, whereas cilostazol- and levcromakalim-induced hypersensitivity were independent of both. All three migraine triggers activated calcitonin gene-related peptide signalling, as both receptor antagonism and antibody neutralisation of calcitonin gene-related peptide were effective inhibitors of hypersensitivity in all three models. Stimulation of trigeminal ganglia and brain stem tissue samples with cilostazol and levcromakalim did not result in release of calcitonin gene-related peptide, and vasodilation following levcromakalim stimulation was independent of CGRP receptor antagonism.

CONCLUSION

The mouse models of glyceryl trinitrate-, cilostazol- and levcromakalim- induced migraine all involve calcitonin gene-related peptide signalling in a complex interplay between different cell/tissue types. These models are useful in the study of migraine mechanisms.

Neurophysiological and biomolecular effects of erenumab in chronic migraine: An open label study

INTRODUCTION

Anti-calcitonin gene-related peptide antibodies proved effective in the preventive treatment of chronic migraine. In this open label study, we aim to assess the effects of erenumab administration on neurophysiological and biomolecular profiles in a representative cohort of chronic migraine patients.

METHODS

Forty patients with a history of chronic migraine for at least 12 months prior to enrollment, and previous failure of at least two different preventive therapies, were enrolled. After a 1-month observation period (T0), patients were treated with erenumab 70 mg s.c. (every 28 days) for a total of three administrations. At week 12, they returned for the end-of-protocol visit (T3). At T0 and T3, patients underwent recording of clinical features, recording of single stimulus (RTh), temporal summation (TST) thresholds of the nociceptive withdrawal reflex, venous blood sampling for miR-382-5p, and miR-34a-5p quantification.

RESULTS

At T3, 31 patients (77.5%) qualified as 30% Responders (reduction in monthly migraine days by at least 30% in the last 4-week observation period). RTh (T0: 15.4 ± 8.1 mA, T3: 19.7 ± 8.2 mA) as well as TST (T0: 11.2 ± 5.8 mA, T3: 13.4 ± 5.0 mA) significantly increased at T3 in 30% Responders (p = 0.001 for both), while we did not observe significant changes in NON-responder patients. MiR-382-5p and miR-34a-5p levels were significantly lower after erenumab administration in the overall study population (p = 0.015, and p = 0.001, respectively), without significant differences between 30% Responder and NON-responder groups.

CONCLUSIONS

Different migraine phenotypes, characterized by different treatment susceptibility, may exist as suggested by the divergent behavior between neurophysiological and biomolecular findings in 30% Responder vs. NON-responder patients.The study protocol was registered at clinicaltrials.gov (NCT04361721).

No central action of CGRP antagonising drugs in the GTN mouse model of migraine

Introduction

Clinically, calcitonin gene-related peptide antagonising drugs are recognized as effective in migraine treatment, but their site of action is debated. Only a small fraction of these compounds pass the blood-brain barrier and accesses the central nervous system. Regardless, it has been argued that the central nervous system is the site of action. Here, we test this hypothesis by bypassing the blood-brain barrier through intracerebroventricular injection of calcitonin gene-related peptide antagonising drugs.

Methods

We used the glyceryl trinitrate (GTN) mouse model, which is well validated by its response to specific migraine drugs. The calcitonin gene-related peptide receptor antagonist olcegepant and the calcitonin gene-related peptide monoclonal antibody ALD405 were administered either intraperitoneally or intracerebroventricularly. The outcome measure was cutaneous mechanical allodynia.

Results

Mice given olcegepant intraperitoneally + GTN on day 1 had a mean 50% withdrawal threshold of 1.2 g in contrast to mice receiving placebo + GTN, which had a threshold of 0.3 g ( p < 0.001). Similarly, in the ALD405 + GTN group, mice had thresholds of 1.2 g versus 0.2 g in the placebo + GTN group ( p < 0.001). However, both drugs were ineffective when delivered intracerebroventricularly, as control and active groups had identical mechanical sensitivity thresholds, 0.2 g versus 0.1 g and 0.1 g versus 0.1 g for olcegepant and ALD405, respectively ( p > 0.99 in both cases).

Discussion

The site of action of olcegepant and of the monoclonal antibody ALD405 is outside the blood-brain barrier in this mouse model of migraine. It is likely that these results can be generalised to all gepants and all antibodies and that the results are relevant for human migraine.